Brigitte Bardot has threatened to follow Gerard Depardieu to Russia unless two elephants under threat of being put down are granted a reprieve.

In a twist to the saga over actor Depardieu's move into tax exile, the veteran animal rights campaigner said she, too, would make a request for Russian nationality.

Russia has granted Depardieu citizenship

French cinema legend Bardot wants the authorities to intervene to save the two middle-aged elephants, Baby and Nepal.

Both have tuberculosis and have been deemed a threat to other animals at the Tete d'Or zoo in Lyon, as well as to human visitors because the disease is highly contagious.

City authorities ordered the elephants to be put down last month, but a petition organised by their original owner, circus master Gilbert Edelstein, resulted in them being granted a temporary reprieve over Christmas.

Bardot said in a statement she would be leaving France if the reprieve was not made permanent.

"If the powers that be have the cowardice and the shamelessness to kill Baby and Nepal ... I have decided to take Russian nationality and quit this country that is nothing more (than) an animal cemetery," Bardot said.

Bardot, 77, has been a high-profile supporter of Depardieu in his spat with the French government over taxes.

The Cyrano de Bergerac and Green Card star has bought a house in neighbouring Belgium and is seeking residency there.

He has also been granted citizenship in Russia, which has a flat income tax rate of 13%.

Last month Bardot said her fellow actor, who was branded "pathetic" by Prime Minister Jean-Marc Ayrault, had been the victim of "extremely unfair persecution".